Eliminating the use of quotes in cases where quotes aren't needed

In most cases we can just use the "if" statement's implicit variable dereferencing instead of using quotes.  In a single case, the "MSVC" variable is defined for visual studio on Windows, and so a string comparison can be elided completely.
Merge pull request #308 from leapmotion/fix-quotedstrwarn

Eliminating the use of quotes in cases where quotes aren't needed